It's just the latest evidence of major restaurant chains scrambling to step up the image of their food as competition from smaller players intensifies

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McDonald's, which is trying to shake its image for serving processed junk food, says it's purging some unpalatable ingredients from its most popular menu items.

Changes announced Monday include making Chicken McNuggets and other items without artificial preservatives and removing high-fructose corn syrup from its burger buns.

The tweaks come as the world's biggest burger chain fights to win back customers.

It's just the latest evidence of major restaurant chains scrambling to step up the image of their food as competition from smaller players intensifies. Dunkin' Donuts has said it will introduce an egg patty with a higher concentration of egg.